Instrument systems for integrated sample processing

ABSTRACT

An integrated system for processing and preparing samples for analysis may include a microfluidic device including a plurality of parallel channel networks for partitioning the samples including various fluids, and connected to a plurality of inlet and outlet reservoirs, at least a portion of the fluids comprising reagents, a holder including a closeable lid hingedly coupled thereto, in which in a closed configuration, the lid secures the microfluidic device in the holder, and in an open configuration, the lid is a stand orienting the microfluidic device at a desired angle to facilitate recovery of partitions or droplets from the partitioned samples generated within the microfluidic device, and an instrument configured to receive the holder and apply a pressure differential between the plurality of inlet and outlet reservoirs to drive fluid movement within the channel networks.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Patent Application No. 62/075,653 filed Nov. 5, 2014, entitled “INSTRUMENT SYSTEMS FOR INTEGRATED SAMPLE PROCESSING,” the disclosure of which is expressly incorporated herein for all purposes by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION

The field of life sciences has experienced dramatic advancement over the last two decades. From the broad commercialization of products that derive from recombinant DNA technology, to the simplification of research, development and diagnostics, enabled by the invention and deployment of critical research tools, such as the polymerase chain reaction, nucleic acid array technologies, robust nucleic acid sequencing technologies, and more recently, the development and commercialization of high throughput next generation sequencing technologies. All of these improvements have combined to advance the fields of biological research, medicine, diagnostics, agricultural biotechnology, and myriad other related fields by leaps and bounds.

Many of these advances in biological analysis and manipulation require complex, multi-step process workflows, as well as multiple highly diverse unit operations, in order to achieve the desired result. Nucleic acid sequencing, for example requires multiple diverse steps in the process workflow (e.g., extraction, purification, amplification, library preparation, etc.) before any sequencing operations are performed. Each workflow process step and unit operation introduces the opportunity for user intervention and its resulting variability, as well as providing opportunities for contamination, adulteration, and other environmental events that can impact the obtaining of accurate data, e.g., sequence information.

The present disclosure describes systems and processes for integrating multiple process workflow steps in a unified system architecture that also integrates simplified sample processing steps.

BRIEF SUMMARY OF THE INVENTION

Provided are integrated systems and processes for use in the preparation of samples for analysis, and particularly for the preparation of nucleic acid containing samples for sequencing analysis.

According to various embodiments of the present invention, an integrated system for processing and preparing samples for analysis comprises a microfluidic device including a plurality of parallel channel networks for partitioning the samples including various fluids, and connected to a plurality of inlet and outlet reservoirs, at least a portion of the fluids comprising reagents, a holder including a closeable lid hingedly coupled thereto, in which in a closed configuration, the lid secures the microfluidic device in the holder, and in an open configuration, the lid comprises a stand orienting the microfluidic device at a desired angle to facilitate recovery of partitions or droplets from the partitioned samples generated within the microfluidic device. The integrated system may further include an instrument configured to receive the holder and apply a pressure differential between the plurality of inlet and outlet reservoirs to drive fluid movement within the channel networks.

In some embodiments, the desired angle at which the microfluidic device is oriented by the lid ranges from 20-70 degrees, 30-60 degrees, 40-50 degrees.

In some embodiments, the desired angle at which the microfluidic device is oriented by the lid is 45 degrees.

In some embodiments, the instrument comprises a retractable tray supporting and seating the holder, and slidable into out of the instrument, a depressible manifold assembly configured to be actuated and lowered to the microfluidic device and to sealably interface with the plurality of inlet and outlet reservoirs, at least one fluid drive component configured to apply the pressure differential between the plurality of inlet and outlet reservoirs, and a controller configured to operate the at least one drive fluid component to apply the pressure differential depending on a mode of operation or according to preprogrammed instructions.

In some embodiments, at least one of the parallel channel networks comprises a plurality of interconnected fluid channels fluidly communicated at a first channel junction, at which an aqueous phase containing at least one of the reagents is combined with a stream of a non-aqueous fluid to partition the aqueous phase into discrete droplets within the non-aqueous fluid, and the partitioned samples are stored in the outlet reservoirs for harvesting, or stored in at least one product storage vessel.

In some embodiments, the plurality of interconnected fluid channels comprises a microfluidic structure having intersecting fluid channels fabricated into a monolithic component part.

In some embodiments, the integrated system further comprises a gasket coupled to the holder and including a plurality of apertures, in which when the lid is in the closed configuration, the gasket is positioned between the reservoirs and the manifold assembly to provide the sealable interface, and the apertures allow pressure communication between at least one of the outlet and the inlet reservoirs and the at least one fluid drive component.

In some embodiments, the integrated system further comprises springs to bias the manifold assembly in a raised position, and a servo motor to actuate and lower the manifold assembly.

In some embodiments, the integrated system further comprises at least one monitoring component interfaced with at least one of the plurality of channel networks and configured to observe and monitor characteristics and properties of the at least one channel network and fluids flowing therein. The at least one monitoring component is selected from the group consisting of: a temperature sensor, a pressure sensor, and a humidity sensor.

In some embodiments, the integrated system further comprises at least one valve to control flow into a segment of at least one channel of the plurality of parallel channel networks by breaking capillary forces acting to draw aqueous fluids into the channel at a point of widening of the channel segment in the valve.

In some embodiments, the at least one valve comprises a passive check valve.

In some embodiments, at least one of the plurality of parallel channel networks comprises a first channel segment fluidly coupled to a source of barcode reagents, a second channel segment fluidly coupled to a source of the samples, the first and second channel segments fluidly connected at a first channel junction, a third channel segment connected to the first and second channel segments at the first channel junction, a fourth channel segment connected to the third channel segment at a second channel junction and connected to a source of partitioning fluid, and a fifth channel segment fluidly coupled to the second channel junction and connected to a channel outlet, The at least one fluid driving system is coupled to at least one of the first, second, third, fourth, and fifth channel segments, and is configured to drive flow of the barcode reagents and the reagents of the sample into the first channel junction to form a reagent mixture in the third channel segment and to drive flow of the reagent mixture and the partitioning fluid into the second channel junction to form droplets of the first reaction mixture in a stream of partitioning fluid within the fifth channel segment.

According to various embodiments of the present invention, a holder assembly comprises a holder body configured to receive a microfluidic device, the microfluidic device including a plurality of parallel channel networks for partitioning various fluids, and a closeable lid hingedly coupled to the holder body. In a closed configuration, the lid secures the microfluidic device in the holder body, and in an open configuration, the lid comprises a stand to orient the microfluidic device at a desired angle to facilitate recovery of partitions or droplets from the partitioned fluids without spilling the fluids.

In some embodiments, the desired angle at which the microfluidic device is oriented by the lid ranges from 20-70 degrees, 30-60 degrees, 40-50 degrees.

In some embodiments, the desired angle at which the microfluidic device is oriented by the lid is 45 degrees.

According to various embodiments of the present invention, a method for measurement of parameters of fluid in samples for analysis in a microfluidic device of an integrated system comprises positioning a line camera in optical communication with a segment of at least one fluid channel of the microfluidic device, imaging, by the at least one line scan camera, in a detection line across the channel segment, and processing, by the at least one line scan camera, images of particulate or droplet based materials of the samples as the materials pass through the detection line, to determine shape, size and corresponding characteristics of the materials, and angling the at least one line camera and the corresponding detection line across the channel segment to increase a resolution of resulting images across the channel segment. An angle at which the at least one line camera and the corresponding detection line are angled across the channel segment ranges from 5-80 degrees from an axis perpendicular to the channel segment.

In some embodiments, the method for measurement further comprises optically communicating the line camera with a post partitioning segment of at least one fluid channel of the microfluidic device, to monitor formed partitions emanating from a partitioning junction of the microfluidic device.

In some embodiments, the method for measurement further comprises optically communicating the line camera with a post partitioning segment of at least one fluid channel of the microfluidic device, to monitor formed partitions emanating from a partitioning junction of the microfluidic device.

In some embodiments, the method for measurement further comprises optically coupling at least one line scan sensor to one or more of a particle inlet channel segment to monitor materials being brought into a partitioning junction to be co-partitioned.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a first level of system architecture as further described herein.

FIG. 2 is an exemplary illustration of a consumable microfluidic component for use in partitioning sample and other materials.

FIGS. 3A, 3B, and 3C illustrate different components of a microfluidic control system.

FIG. 4 schematically illustrates the structure of an example optical detection system for integration into overall instrument systems described herein.

FIG. 5 schematically illustrates an alternate detection scheme for use in imaging materials within microchannels.

FIG. 6 illustrates an exemplary processing workflow, some or all of which may be integrated into a unified system architecture.

FIG. 7 schematically illustrates the integration of a nucleic acid size fragment selection component into a microfluidic partitioning component.

FIG. 8 illustrates a monitored pressure profile across a microfluidic channel network for use in controlling fluidic flows through the channel network.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to devices and systems for use in apportioning reagents and other materials into extremely large numbers of partitions in a controllable manner. In particularly preferred aspects, these devices and systems are useful in apportioning multiple different reagents and other materials, including for example, beads, particles and/or microcapsules into large numbers of partitions along with other reagents and materials. In particularly preferred aspects, the devices and systems apportion reagents and other materials into droplets in an emulsion in which reactions may be carried out in relative isolation from the reagents and materials included within different partitions or droplets. Also included are systems that include the above devices and systems for conducting a variety of integrated reactions and analyses using the apportioned reagents and other materials. Thus, the systems and processes of the present invention can be used with any devices and any systems such as those outlined in U.S. Provisional Patent Application No. 62/075,653, the full disclosure of which is expressly incorporated by reference in its entirety for all purposes, specifically including the Figures, Legends and descriptions of the Figures and components therein.

I. Partitioning Systems

The systems described herein include instrumentation, components, and reagents for use in partitioning materials and reagents. In preferred aspects, the systems are used in the delivery of highly complex reagent sets to discrete partitions for use in any of a variety of different analytical and preparative operations. The systems described herein also optionally include both upstream and downstream subsystems that may be integrated with such instrument systems.

The overall architecture of these systems typically includes a partitioning component, which is schematically illustrated in FIG. 1. As shown, the architecture 100, includes a fluidics component 102 (illustrated as an interconnected fluid conduit network 104), that is interfaced with one or more reagent and/or product fluid storage vessels, e.g., vessels 106-116. The fluidics component includes a network of interconnected fluid conduits through which the various fluids are moved from their storage vessels, and brought together in order to apportion the reagents and other materials into different partitions, which partitions are then directed to the product storage vessel(s), e.g., vessel 116.

The fluidics component 102 is typically interfaced with one or more fluid drive components, such as pumps 118-126, and/or optional pump 128, which apply a fluid driving force to the fluids within the vessels to drive fluid flow through the fluidic component. By way of example, these fluid drive components may apply one or both of a positive and/or negative pressure to the fluidic component, or to the vessels connected thereto, to drive fluid flows through the fluid conduits. Further, although shown as multiple independent pressure sources, the pressure sources may comprise a single pressure source that applies pressure through a manifold to one or more of the various channel termini, or a negative pressure to a single outlet channel terminus, e.g., pump 128 at reservoir 116.

The instrument system 100 also optionally includes one or more environmental control interfaces, e.g., environmental control interface 130 operably coupled to the fluidic component, e.g., for maintaining the fluidic component at a desired temperature, desired humidity, desired pressure, or otherwise imparting environmental control. A number of additional components may optionally be interfaced with the fluidics component and/or one or more of the reagent or product storage vessels 106-116, including, e.g., optical detection systems for monitoring the movement of the fluids and/or partitions through the fluidic component, and/or in the reagent and or product reservoirs, etc., additional liquid handling components for delivering reagents and/or products to or from their respective storage vessels to or from integrated subsystems, and the like.

The instrument system also may include integrated control software or firmware for instructing the operation of the various components of the system, typically programmed into a connected processor 132, which may be integrated into the instrument itself, or maintained on a directly or wirelessly connected, but separate processor, e.g., a computer, tablet, smartphone, or the like, for controlling the operation of, and/or for obtaining data from the various subsystems and/or components of the overall system.

II. Fluidics Component

As noted above, the fluidics component of the systems described herein is typically configured to allocate reagents to different partitions, and particularly to create those partitions as droplets in an emulsion, e.g., an aqueous droplet in oil emulsion. In accordance with this objective, the fluidic component typically includes a plurality of channel or conduit segments that communicate at a first channel junction at which an aqueous phase containing one or more of the reagents is combined with a stream of a non-aqueous fluid, such as an oil like a fluorinated oil, for partitioning the aqueous phase into discrete droplets within the flowing oil stream. While any of a variety of fluidic configurations may be used to provide this channel junction, including, e.g., connected fluid tubing, channels, conduits or the like, in particularly preferred aspects, the fluidic component comprises a microfluidic structure that has intersecting fluid channels fabricated into a monolithic component part. Examples of such microfluidic structures have been generally described in the art for a variety of different uses, including, e.g., nucleic acid and protein separations and analysis, cell counting and/or sorting applications, high throughput assays for, e.g., pharmaceutical candidate screening, and the like.

Typically, the microfluidics component of the system includes a set of intersecting fluid conduits or channels that have one or more cross sectional dimensions of less than about 200 um, preferably less than about 100 um, with some cross sectional dimensions being less than about 50 um, less than about 40 um, less than about 30 um, less than about 20 um, less than about 10 um, and in some cases less than or equal to about 5 um. Examples of microfluidic structures that are particularly useful in generating partitions are described herein and in U.S. Provisional Patent Application No. 61/977,804, filed Apr. 4, 2014, the full disclosure of which is incorporated herein by reference in its entirety for all purposes.

FIG. 2 shows an exemplary microfluidic channel structure for use in generating partitioned reagents, and particularly for use in co-partitioning two or more different reagents or materials into individual partitions. As shown, the microfluidic component 200 provides one or more channel network modules 250 for generating partitioned reagent compositions. As shown, the channel network module 250 includes a basic architecture that includes a first channel junction 210 linking channel segments 202, 204 and 206, as well as channel segment 208 that links first junction 210 to second channel junction 222. Also linked to second junction 222 are channel segments 224, 226 and 228.

As illustrated, channel segment 202 is also fluidly coupled to reservoir 230, that provides, for example, a source of additional reagents such as microcapsules, beads, particles or the like, optionally including one or more encapsulated or associated reagents, suspended in an aqueous solution. Each of channel segments 204 and 206 are similarly fluidly coupled to reagent storage vessel or fluid reservoir 232, which may provide for example, a source of sample material as well as other reagents to be partitioned along with the microcapsules. As noted previously, although illustrated as both channel segments 204 and 206 being coupled to the same reservoir 232, these channel segments are optionally coupled to different reservoirs for introducing different reagents or materials to be partitioned along with the reagents from reservoir 230.

As shown, each of channel segments 202, 204 and 206 are provided with optional additional fluid control structures, such as passive fluid valve 236. These valves optionally provide for controlled filling of the overall devices by breaking the capillary forces that draw the aqueous fluids into the device at the point of widening of the channel segment in the valve structure. Briefly, aqueous fluids are introduced first into the device in reservoirs 230 and 232, at which point these fluids will be drawn by capillary action into their respective channel segments. Upon reaching the valve structure, the widened channel will break the capillary forces, and fluid flow will stop until acted upon by outside forces, e.g., positive or negative pressures, driving the fluid into and through the valve structure. These structures are also particularly useful as flow regulators for instances where beads, microcapsules or the like are included within the reagent streams, e.g., to ensure a regularized flow of such particles into the various channel junctions.

Also shown in channel segment 202 is a funneling structure 252, that provides reduced system failure due to channel clogging, and also provides an efficient gathering structure for materials from reservoir 230, e.g., particles, beads or microcapsules, and regulation of their flow. As also shown, in some cases, the connection of channel segment 202 with reservoir 230, as well as the junctions of one or more or all of the channel segments and their respective reservoirs, may be provided with additional functional elements, such as filtering structures 254, e.g., pillars, posts, tortuous fluid paths, or other obstructive structures to prevent unwanted particulate matter from entering or proceeding through the channel segments.

First junction 210 is fluidly coupled to second junction 222. Also coupled to channel junction 222 are channel segments 224 and 226 that are, in turn fluidly coupled to reservoir 234, which may provide, for example, partitioning fluid that is immiscible with the aqueous fluids flowing from junction 210. Again, channel segments 224 and 226 are illustrated as being coupled to the same reservoir 234, although they may be optionally coupled to different reservoirs, e.g., where each channel segment is desired to deliver a different composition to junction 222, e.g., partitioning fluids having different make up, including differing reagents, or the like.

In exemplary operation, a first fluid reagent, e.g., including microcapsules or other reagents, that is provided in reservoir 230 is flowed through channel segment 202 into first channel junction 210. Within junction 210, the aqueous first fluid reagent solution is contacted with the aqueous fluids, e.g., a second reagent fluid, from reservoir 232, as introduced by channel segments 204 and 206. While illustrated as two channel segments 204 and 206, it will be appreciated that fewer (1) or more channel segments may be connected at junction 210. For example, in some cases, junction 210 may comprise a T junction at which a single side channel meets with channel segment 202 in junction 210.

The combined aqueous fluid stream is then flowed through channel segment 208 into second junction 222. Within channel junction 222, the aqueous fluid stream flowing through channel segment 208, is formed into droplets within the immiscible partitioning fluid introduced from channel segments 224 and 226. In some cases, one or both of the partitioning junctions, e.g., junction 222 and one or more of the channel segments coupled to that junction, e.g., channel segments 208, 224, 226 and 228, may be further configured to optimize the partitioning process at the junction.

Further, although illustrated as a cross channel intersection at which aqueous fluids are flowed through channel segment 208 into the partitioning junction 222 to be partitioned by the immiscible fluids from channel segments 224 and 226, and flowed into channel segment 228, as described elsewhere herein, partitioning structure within a microfluidic device of the invention may comprise a number of different structures.

As described in greater detail below, the flow of the combined first and second reagent fluids into junction 222, and optionally, the rate of flow of the other aqueous fluids and/or partitioning fluid through each of junctions 210 and 222, are controlled to provide for a desired level of partitioning, e.g., to control the number of frequency and size of the droplets formed, as well as control apportionment of other materials, e.g., microcapsules, beads or the like, in the droplets.

Once the reagents are allocated into separate partitions, they are flowed through channel segment 228 and into a recovery structure or zone, where they may be readily harvested. As shown, the recovery zone includes, e.g., product storage vessel or outlet reservoir 238. Alternatively, the recovery zone may include any of a number of different interfaces, including fluidic interfaces with tubes, wells, additional fluidic networks, or the like. In some cases, where the recovery zone comprises an outlet reservoir, the outlet reservoir will be structured to have a volume that is greater than the expected volume of fluids flowing into that reservoir. In its simplest sense, the outlet reservoir may, in some cases, have a volume capacity that is equal to or greater than the combined volume of the input reservoirs for the system, e.g., reservoirs 230, 232 and 234.

In certain aspects, and as alluded to above, at least one of the aqueous reagents to be co-partitioned will include a microcapsule, bead or other microparticle component, referred to herein as a bead. As such, one or more channel segments may be fluidly coupled to a source of such beads. Typically, such beads will include as a part of their composition one or more additional reagents that are associated with the bead, and as a result, are co-partitioned along with the other reagents. In many cases, the reagents associated with the beads are releasably associated with, e.g., capable of being released from, the beads, such that they may be released into the partition to more freely interact with other reagents within the various partitions. Such release may be driven by the controlled application of a particular stimulus, e.g., application of a thermal, chemical or mechanical stimulus. By providing reagents associated with the beads, one may better control the amount of such reagents, the composition of such reagents being co-partitioned, and the initiation of reactions through the controlled release of such reagents.

By way of example, in some cases, the beads may be provided with oligonucleotides releasably associated with the beads, where the oligonucleotides represent members of a diverse nucleic acid barcode library, whereby an individual bead may include a large number of oligonucleotides, but only a single type of barcode sequence included among those oligonucleotides. The barcode sequences are co-partitioned with sample material components, e.g., nucleic acids, and used to barcode portions of those sample components. The barcoding then allows subsequent processing of the sequence data obtained, by matching barcodes as having derived from possibly structurally related sequence portions. The use of such barcode beads is described in detail in U.S. patent application Ser. No. 14/316,318, filed Jun. 26, 2014, and incorporated herein by reference in its entirety for all purposes.

The microfluidic component is preferably provided as a replaceable consumable component that can be readily replaced within the instrument system, e.g., as shown in FIG. 2. For example, microfluidic devices or chips may be provided that include the integrated channel networks described herein, and optionally include at least a portion of the applicable reservoirs, or an interface for an attachable reservoir, reagent source or recovery component as applicable. Fabrication and use of microfluidic devices has been described for a wide range of applications, as noted above. Such devices may generally be fabricated from organic materials, inorganic materials, or both. For example, microfluidic devices may be fabricated from organic materials, such as polyethylene or polyethylene derivatives, such as cyclic olefin copolymers (COC), polymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS), polycarbonate, polystyrene, polypropylene, or the like, or they may be fabricated in whole or in part from inorganic materials, such as silicon, or other silica based materials, e.g., glass, quartz, fused silica, borosilicate glass, or the like. Particularly useful microfluidic device structures and materials are described in Provisional U.S. Patent Application No. 61/977,804, filed Apr. 4, 2014, previously incorporated herein by reference.

III. Flow Controllers

As noted with reference to FIG. 1, above, typically, such replaceable microfluidics structures are integrated within a larger instrument system that, as noted above, includes a number of other components for operation of the system, as well as optional additional system components used for monitoring system operation, and/or for processes in a workflow that sit upstream and/or downstream of the partitioning processes.

In particular, as noted above, the overall system typically includes one or more fluid driving systems for driving flow of the fluid reagents through the channel structures within the fluidic component(s). Fluid driving systems can include any of a variety of different fluid driving mechanisms. In preferred aspects, these fluid driving systems will include one or more pressure sources interfaced with the channel structures to apply a driving pressure to either push or pull fluids through the channel networks. In particularly preferred aspects, these pressure sources include one or more pumps that are interfaced with one or more of the inlets or outlets to the various channel segments in the channel network.

As will be appreciated, in some cases, fluids are driven through the channel network through the application of positive pressures by applying pressures to each of the inlet reservoirs through the interconnected channel segments. In such cases, one or more pressure sources may be interfaced with each reservoir through an appropriate manifold or connector structure. Alternatively, a separately controllable pressure source may be applied to each of one or more of the various different inlet reservoirs, in order to independently control the application of pressure to different reservoirs. Such independent control can be useful where it is desired to adjust or modify of flow profiles in different channel segments over time or from one application to another. Pressure pumps, whether for application of positive or negative pressure or both, may include any of a variety of pumps for application of pressure heads to fluid materials, including, for example, diaphragm pumps, simple syringe pumps, or other positive displacement pumps, pressure tanks or cartridges along with pressure regulator mechanisms, e.g., that are charged with a standing pressure, or the like.

As noted, in certain cases, a negative pressure source may be applied to the outlet of the channel network, e.g., by interfacing the negative pressure source with outlet reservoir 238 shown in FIG. 2. By applying a negative pressure to the outlet, the ratios of fluid flow within all of the interconnected channels is generally maintained as relatively constant, e.g., flow within individual channels are not separately regulated through the applied driving force. As a result, flow characteristics are generally a result of one or more of the channel geometries, e.g., cross section and length which impact fluidic resistance through such channels, fluid the properties within the various channel segments, e.g., viscosity, and the like. While not providing for individual flow control within separate channel segments of the device, it will be appreciated that one can program flow rates into a channel structure through the design of the channel network, e.g., by providing varied channel dimensions to impact flow rates under a given driving force. Additionally, use of a single vacuum source coupled to the outlet of the channel network provides advantages of simplicity in having only a single driving force applied to the system.

In alternative or additional aspects, other fluid driving mechanisms may be employed, including for example, driving systems that are at least partially integrated into the fluid channels themselves, such as electrokinetic pumping structures, mechanically actuated pumping systems, e.g., diaphragm pumps integrated into the fluidic structures, centrifugal fluid driving, e.g., through rotor based fluidic components that drive fluid flow outward from a central reservoir through a radially extending fluidic network, by rapidly spinning the rotor, or through capillary force or wicking driving mechanisms.

The pump(s) are typically interfaced with the channel structures by a sealed junction between the pump, or conduit or manifold connected to the pump, and a terminus of the particular channel, e.g., through a reservoir or other interfacing component. In particular, with respect to the device illustrated in FIG. 2, a pump outlet may be interfaced with the channel network by mating the pump outlet to the opening of the reservoir with an intervening gasket or sealing element disposed between the two. The gasket may be an integral part of the microfluidic structure, the pump outlet, or both, or it may be a separate component that is placed between the microfluidic structure and the pump outlet. For example, an integrated gasket element may be molded over the top layer of the microfluidic device, e.g., as the upper surface of the reservoirs, as a second deformable material, e.g., a thermoplastic elastomer molded onto the upper lip of the reservoir that is molded from the same rigid material as the underlying microfluidic structure. Although described with reference to pressed interfaces of pump outlets to reservoirs on microfluidic devices, it will be appreciated that a variety of different interface components may be employed, including any of a variety of different types of tubing couplings (e.g., barbed, quick connect, press fit, etc.) to interface pressure sources to channel networks. Likewise, the pressure sources may be interfaced to upstream or downstream process components and communicated to the channel networks through appropriate interface components between the fluidic component in the partitioning system and the upstream or downstream process component. For example, where multiple integrated components are fluidically coupled together, application of a pressure to one end of the integrated fluidic system may be used to drive fluids through the conduits of each integrated component as well as to drive fluids from one component to another.

In some cases, both positive and negative pressures may be employed in a single process run. For example, in some cases, it may be desirable to process a partitioning run through a microfluidic channel network. Upon conclusion of the run, it may be desirable to reverse the flow through the device, to drive some portion of the excess non-aqueous component back out of the outlet reservoir back through the channel network, in order to reduce the amount of the non-aqueous phase that will be present in the outlet reservoir when being accessed by the user. In such cases, a pressure may be applied in one direction, either positive or negative, during the partitioning run to create the droplets through the microfluidic device, e.g., device 200 in FIG. 2, that accumulate in reservoir 238 along with excess non-aqueous phase material, which will remain at the bottom of the reservoir, e.g., at the interface with the channel 228. By then reversing the direction of pressure, either positive or negative, one may drive excess non-aqueous material back into the channel network, e.g., channel 228.

Additional control elements may be included coupled to the pumps of the system, including valves that may be integrated into manifolds, for switching applied pressures as among different channel segments in a single fluidic structure or between multiple channel structures in separate fluid components. Likewise, control elements may also be integrated into the fluidics components. For example, valving structures may be included within the channel network to controllably interrupt flow of fluids in or through one or more channel segments. Examples of such valves include the passive valves described above, as well as active controllable valve structures, such as depressible diaphragms or compressible channel segments, that may be actuated to restrict or stop flow through a given channel segment.

FIGS. 3A-3C illustrate components of an exemplary instrument/system architecture for interfacing with microfluidic components, as described above. As shown in FIG. 3A, a microfluidic device 302 that includes multiple parallel channel networks all connected to various inlet and outlet reservoirs, e.g., reservoirs 304 and 306, is placed into a secondary holder 310 that includes a closeable lid 312, to secure the device within the holder. Once the lid 312 is closed over the microfluidic device 302 in the secondary holder 310, an optional gasket 314 may be placed over the top of the reservoirs, e.g., reservoirs 304 and 306, protruding from the top of the secondary holder 310. As shown, gasket 314 includes apertures 316 to allow pressure communication between the reservoirs, e.g., reservoirs 304 and 306, and an interfaced instrument, through the gasket. As shown, gasket 314 also includes securing points 318 that are able to latch onto complementary hooks or other tabs 320 on the secondary holder to secure the gasket 314 in place. Also as shown, secondary holder 310 is assembled such that when the lid portion 312 is fully opened, it creates a stand for the secondary holder 310 and a microfluidic device, e.g., microfluidic device 302, contained therein, retaining the microfluidic device 302 at an appropriate orientation, e.g., at a supported angle, for recovering partitions or droplets generated within the microfluidic device 302. Typically, the supported angle at which the microfluidic device 302 is oriented by the lid 312 will range from about 20-70 degrees, more typically about 30-60 degrees, preferrably 40-50 degrees, or in some cases approximately 45 degrees. Though recited in terms of certain ranges, it will be understood that all ranges from the lowest of the lower limits to the highest of the upper limits are included, including all intermediate ranges or specific angles, within this full range or any specifically recited range. Such angles provide an improved or optimized configuration for recovering the partitions or droplets generated within the microfluidic device 302 while minimizing or preventing spillage of the fluids within the microfluidic device 302.

FIG. 3B shows a perspective view of an instrument system 350 while FIG. 3C illustrates a side view of the instrument system 350. As shown, and with reference to FIG. 3A, a microfluidic device 302 may be placed into a secondary holder 310 that is, in turn, placed upon a retractable tray 322, that moves is slidable into and out of the instrument system 350. The retractable tray 322 is positioned on guide rails 324 that extend in a horizontal direction of the instrument system 350 (as shown by the arrows in FIG. 3C) and allow the retractable tray 322 to slide into and out of a slot formed in the housing 354 when driven by a driving mechanism. In some embodiments, the driving mechanism may include a motor part (not shown) to transmit rotation power, and a moving link part (not shown) extending from the motor part towards the guide rails 324, such that the moving link part is connected to the guide rails 324 to slide the guide rails 324 in the horizontal direction when the motor part is operated. Pinion gears (not shown) may be formed on the moving link part and rack gears (not shown) extending in the horizontal direction may be formed on the guide rails 324 such that the pinion gears are engaged with the rack gears, and when the motor part is operated, the moving link part is rotated and the pinion gears are rotated and moved along the rack gears to slide the retractable tray 322, positioned on the guide rails 324, into and out of the housing 354.

Once secured within the instrument system 350, a depressible manifold assembly 326 is lowered into contact with the reservoirs, e.g., reservoirs 304 and 306 in the microfluidic device 302, making sealed contact between the manifold assembly 326 and the reservoirs 304 and 306 by virtue of intervening gasket 314. Depressible manifold assembly 326 is actuated and lowered against the microfluidic device 302 through incorporated servo motor 328 that controls the movement of the manifold assembly 326, e.g., through a rotating cam (not shown) that is positioned to push the manifold assembly 326 down against microfluidic device 302 and gasket 314, or through another linkage. The manifold assembly 326 is biased in a raised position by springs 330. Once the manifold assembly 326 is securely interfaced with the reservoirs, e.g., reservoirs 304 and 306, on the microfluidic device 302, pressures are delivered to one or more reservoirs, e.g., reservoirs 304 and 306, within each channel network within the microfluidic device 302, depending upon the mode in which the system is operating, e.g., pressure or vacuum drive. The pressures are supplied to the appropriate conduits within the manifold 326 from one or both of pumps 332 and 334. Operation of the system is controlled through onboard control processor, shown as circuit board 356, which is programmed to operate the pumps in accordance with preprogrammed instructions, e.g., for requisite times or to be responsive to other inputs, e.g., sensors or user inputs. Also shown is a user button 338 that is depressed by the user to execute the control of the system, e.g., to extend and retract the tray 322 prior to a run, and to commence a run. Indicator lights 340 are provided to indicate to the user the status of the instrument and/or system run. The instrument components are secured to a frame 352 and covered within housing 354.

IV. Environmental Control

In addition to flow control components, the systems described herein may additionally or alternatively include other interfaced components, such as environmental control components, monitoring components, and other integrated elements.

In some cases, the systems may include environmental control elements for controlling parameters in which the channel networks, reagent vessels, and/or product reservoirs are disposed. In many cases, it will be desirable to maintain controlled temperatures for one or more of the fluidic components or the elements thereof. For example, when employing transient reactants, it may be desirable to maintain cooler temperatures to preserve those reagents. Likewise, in many cases partitioning systems may operate more optimally at a set temperature, and maintaining the system at such temperature will reduce run-to-run variability. Temperature controllers may include any of a variety of different temperature control systems, including simple heaters and coolers, fans or radiators, interfaced with the fluidics component portion of the system. In preferred aspects, temperature control may be provided through a thermoelectric heater/cooler that is directly contacted with the device, or a thermal conductor that is contacted with the device, in order to control its temperature. Thermoelectric coolers are widely available and can generally be configured to apply temperature control to a wide variety of different structures and materials. The temperature control systems will typically be included along with temperature sensing systems for monitoring the temperature of the system or key portions of it, e.g., where the fluidics components are placed, so as to provide feedback control to the overall temperature control system.

In addition to temperature control, the systems may likewise provide control of other environmental characteristics, such as providing a controlled humidity level within the instrument, and/or providing a light or air sealed environment, e.g., to prevent light damage or potential contamination from external sources.

V. Monitoring and Detection

The systems described herein also optionally include other monitoring components interfaced with the fluidics components. Such monitoring systems include, for example, pressure monitoring systems, level indicator systems, e.g., for monitoring reagent levels within reservoirs, and optical detection systems, for observing fluids or other materials within channels within the fluidics components.

A. Pressure

A variety of different monitoring systems may be included, such as pressure monitoring systems that may allow identification of plugged channels, air bubbles, exhaustion of one or more reagents, e.g., that may signal the completion of a given operation, or real time feedback of fluid flows, e.g., indicating viscosity by virtue of back pressures, etc. Such pressure monitoring systems may often include one or more pressure sensors interfaced with one or more fluidic channels, reservoirs or interfacing components, e.g., within the lines connecting the pumps to the reservoirs of the device, or integrated into other conduits coupled to other reservoirs. By way of example, where a positive pressure is applied to multiple inlet reservoirs, pressure sensors coupled to those inlet reservoirs can allow the detection of a channel clog which may be accompanied by a pressure increase, or injection of air through a channel which may accompany exhaustion of one or more reagents from a reservoir, which may be accompanied by a pressure drop. Likewise, pressure sensors coupled to a reservoir to which a negative pressure is applied may similarly identify perturbations in pressure that may be indicative of similar failures or occurrences. With reference to FIG. 1, pressure sensors may be optionally integrated into one or more of the lines connecting the pumps 118-128 (shown as dashed lines), or integrated directly into the reservoirs 106-116, disposed at the termini of the various channel segments in the fluidic channel network 104. The sensors incorporated into the instrument may typically be operably coupled to the controller that is integrated into the instrument, e.g., on circuit board 356 shown in FIG. 3B. Alternatively or additionally, the sensors may be linked, e.g., through appropriate connectors, to an external processor for recording and monitoring of signals from those sensors.

As will be appreciated, when in normal operation, it would be expected that the pressure profiles at the one or more sensors would be expected to remain relatively steady. However, upon a particular failure event, such as aspiration of air into a channel segment, or a blockage at one or more channel segments or intersections, would be expected to cause a perturbation in the steady state pressure profiles. For example, for a system as shown in FIG. 1, that includes an applied negative pressure at an outlet reservoir, e.g., reservoir 116 with an integrated pressure sensor, normal operation of the system would be expected to have a relatively steady state of this negative pressure exhibited at the reservoir. However, in the event of a system disturbance, such as exhaustion of a reagent in one or more of reservoirs 106-114, and resulting aspiration of air into the channels of the system, one would expect to see a reduction in the negative pressure (or an increase in pressure) at the outlet reservoir resulting from the sudden decrease in fluidic resistance in the channel network resulting from the introduction of air. By monitoring the pressure profile, the system may initiate changes in operation in response to such perturbations, including, e.g., shut down of the pumps, triggering of alarms, or other measures, in order to void damaging failure events, e.g., to the system or the materials being processed therein. As will be appreciated, pressure profiles would be similarly monitorable when using individually applied pressures at multiple reservoirs/channel termini. For example, for positive applied pressures, introduction of air into channels would be expected to cause a drop in pressure at an inlet reservoir, while clogs or obstructions would be expected to result in increases in pressures at the inlets of a given clogged channel or channels.

In some cases, one or more pressure sensors may be integrated within the manifold or pressure lines that connect to one or more of the reservoirs or other channel termini, as described herein. A variety of pressure sensor types may be integrated into the systems described herein. For example, small scale solid state pressure sensors may be coupled, in-line, with pressure or vacuum lines connected to the reservoirs of the fluidic components, in order to measure pressure within those lines and at those reservoirs. As with the pumps described herein, pressure sensors may be integrated with one or more of the reservoirs, including the outlet and inlet reservoirs, as applicable. In some cases, each pressure conduit connected to a reservoir within a device may include a pressure sensor for monitoring pressures at such reservoirs.

In operation, the pressure sensing system is used to identify pressure perturbations that signal system failures or end-of-run events, such as channel clogs, air aspiration through channels, e.g., from reagent exhaustion, or the like. In particular, the pressure sensing system is used to trigger system operations when the steady state pressures measured by the pressure sensing system deviate above or below a threshold amount. Upon occurrence of such a perturbation, the system may be configured to shut down, or reduce applied pressures, or initiate other mitigation measures to avoid adulterating the overall system, e.g., by drawing fluids into the pumping system, or manifold. In certain aspects, the system will be configured to shut down or reduce applied pressures when the steady state pressure measured in one or more channel segments deviates from the steady state pressure by more than 10%, more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, or more.

In addition to or as an alternative to the pressure sensors described above, one or more flow sensors may also be integrated into the system, e.g., within the manifold or flow lines of the system, in order to monitor flow through the monitored conduit. As with the pressure sensors, these flow sensors may provide indications of excessive flow rates within one or more of the conduits feeding the fluidic device, as well as provide indications of perturbations in that flow resulting from system problems or fluidics problems, e.g., resulting from channel occlusions or constrictions, exhaustion of one or more fluid reagents, etc.

B. Optical Monitoring and Detection

In addition to pressure sensors, the systems described herein may also include optical sensors for measurement of a variety of different parameters within the fluid components of the system, as well as within other parts of the system. For example, in at least one example, an optical sensor is positioned within the system such that it is in optical communication with one or more of the fluid channels in the fluid component. The optical sensor is typically positioned adjacent one or more channels in the fluid component, so that it is able to detect the passage of material through the particular channel segment. The detection of materials may be by virtue of the change in optical properties of the fluids flowing through the channel, e.g., light scattering, refractive index, or by virtue of the presence of optically detectable species, e.g., fluorophores, chromophores, colloidal materials, or the like, within the fluid conduits.

In many cases, the optical detection system optionally includes one or more light sources to direct illumination at the channel segment. The directed light may enhance aspects of the detection process, e.g., providing contrasting light or excitation light in the illumination of the contents of the channel. In some cases, the light source may be an excitation light source for exciting fluorescent components within the channel segment that will emit fluorescent signals in response. These fluorescent signals are then detected by the optical sensor.

FIG. 4 schematically illustrates an example of an optical detection system for monitoring materials within fluidic channels of the fluidics component of the systems described herein. As shown, the optical detection system 400 typically includes an optical train 402 placed in optical communication with one or more channel segments within the fluidic component, e.g., channel segment 404. In particular, optical train 402 is placed within optical communication with channel segment 404 in order to optically interrogate the channel segment and/or its contents, e.g., fluid 406 and particles or droplets 408. Generally, the optical train will typically include a collection of optical components used for conveying the optical signals from the channel segments to an associated detector or detectors. For example, optical trains may include an objective lens 410 for receiving optical signals from the fluid channel 404, as well as associated optical components, e.g., lenses 412 and 414, spectral filters and dichroics 416 and 418, and spatial filters, e.g., filter 420, for directing those optical signals to a detector or sensor 422 (and one or more optional additional sensors, e.g., sensor 424), such as a CCD or CMOS camera, PMT, photodiode, or other light detecting device.

In some cases, the optical detection system 400 may operate as a light microscope to detect and monitor materials as they pass through the channel segment(s) in question. In such cases, the optical train 402 may include spatial filters, such as confocal optics, e.g., filter 420, as well as an associated light source 426, in order to increase contrast for the materials within the channel segment.

In some cases, the optical detection system may alternatively, or additionally be configured to operate as a fluorescence detection microscope for monitoring fluorescent or fluorescently labeled materials passing through the channel segments. In the case of a fluorescence detection system, light source 426 may be an excitation light source, e.g., configured to illuminate the contents of a channel at a wavelength that excites fluorescence from the materials within the channel segment. In such cases, the optical train 402, may additionally be configured with filter optics to allow the detection of fluorescent emissions from the channel without interference from the excitation light source 426. This is typically accomplished through the incorporation of cut-off or narrow band pass filters, e.g., filter 416 within the optical train to filter out the excitation wavelength while permitting light of the wavelengths emitted by the fluorescent species to pass and be detected.

In particularly preferred aspects, the optical sensor is provided optically coupled to one or more of a particle inlet channel segment (through which beads or other particles are injected into the partitioning region of the fluidic component of the system), e.g., channel segment 202 of FIG. 2, to monitor the materials being brought into the partitioning junction, e.g., monitoring the frequency and flow rates of particles that are to be co-partitioned in the partitioning junction. Alternatively or additionally, the optical detector may be positioned in optical communication with the post partitioning channel segment of the fluidic component, e.g., channel segment 228, to allow the monitoring of the formed partitions emanating from the partitioning junction of the fluidic device or structure. In particular, it is highly desirable to be able to monitor and maintain control of the flow of particles that are being introduced into the partitioning region, and to monitor and control the flow and characteristics of partitions as they are being generated in order to ensure the proper flow rates and generation frequencies for the partitions, as well as to understand the efficiency of the partitioning process.

In a particular example, the optical sensor is used to monitor and detect partitions as they pass a particular point in the channel segment. In such cases, the optical sensor may be used to measure physical characteristics of the partitions, or their components, as they pass the position in the channel, such as the size, shape, speed or frequency of the partitions as they pass the detector. In other cases, the optical detector or sensor 422 may be configured to detect some other characteristics of the partitions as they pass the detector or sensor 422, e.g., relating to the contents of the partitions.

As noted above, in some cases, the optical detection system will be configured to monitor aspects of the contents of the created partitions. For example, in some cases, materials that are to be co-partitioned into individual partitions may be monitored to detect the relative ratio of the co-partitioned materials. By way of example, two fluid borne materials, e.g., a reagent, and a bead population, may each be differentially optically labeled, and the optical detection system is configured to resolve the contribution of these materials in the resulting partitions.

In an example system, two optically resolvable fluorescent dyes may be separately suspended into each of the first reagent and the second reagents that are to be co-partitioned. The relative ratio of the first and second reagents in the resulting partition will be ascertainable by detecting the fluorescent signals associated with each fluorescent dye in the resulting partition. Accordingly, the optical detection system will typically be configured for at least two-color fluorescent optics. Such two color systems typically include one or more light sources that provide excitation light at the appropriate wavelengths to excite the different fluorescent dyes in the channel segment. These systems also typically include optical trains that differentially direct the fluorescent emissions from those dyes to different optical detectors or regions on the same detector. With reference to FIG. 4, for example, two optically distinguishable fluorescent dyes may be co-partitioned into droplets, e.g., droplets 408 within channel segment 404. Upon excitation of those fluorescent dyes by light source 426, two optically resolvable fluorescent signals are emitted from the droplets 408, shown as solid arrow 428. The mixed fluorescent signals, along with transient excitation light are collected through objective 410 and passed through optical train 402. Excitation light is filtered out of the signal path by inclusion of an appropriate filter, e.g., filter 416, which may include one or more cut-off or notch filters that pass the fluorescent light wavelengths while rejecting the excitation wavelengths. The mixed fluorescent signals are then directed toward dichroic mirror 420, which allows one of the fluorescent signals (shown by arrow 430) to pass through to a first detector 422, while reflecting a second, spectrally different fluorescent signal (shown by arrow 432), to second detector 424.

The intensities of each fluorescent signals associated with each dye, are reflective of the concentration of those dyes within the droplets. As such, by comparing the ratio of the signal from each fluorescent dye, one can determine the relative ratio of the first and second fluids within the partition. Further, by comparing the detected fluorescence to known extinction coefficients for the fluorescent dyes, as well as the size of observed region, e.g., a droplet, one can determine the concentration of each component within a droplet. As will be appreciated, where looking to partition particle based reagents into droplets, when using a fluorescently labeled particle, these systems also will allow one to ascertain the relative number of particles within a partition, as well as identifying partitions that contain no particles.

In other aspects, the optical detection systems may be used to determine other characteristics of the materials, particles, partitions or the like, flowing through the channel segments, including, for example, droplet or particle size, shape, flow rate, flow frequency, and other characteristics. In at least one aspect, optical detectors provided are configured to better measure these characteristics. In one aspect, this is achieved through the incorporation of a line scan camera or detector, e.g., camera 510, into the optical system, that images across a channel segment in a detection line in order to process images of the materials as they pass through the detection line. This is schematically illustrated in FIG. 5, top panel. As shown, a channel segment 502 is provided wherein materials, and particularly particulate or droplet based materials are being transported. The optical detection system images a line across the channel segment 502 (indicated as image zone 504). Because the line scan camera employs a line scanner, rather than a two-dimensional array of pixels associated with other camera types, it results in substantially less image processing complexity, allowing greater flexibility of operation.

In addition to using a line scan camera system, in some cases, it is desirable to provide higher resolution imaging using such camera systems by angling the detection line across the channel segment 502, as shown in FIG. 5, bottom panel. In particular, assuming a linear, one-dimensional array of pixels in a line scan camera (schematically illustrated as pixels 506 in camera 508), one would expect an image that is reflective of those pixels (schematically illustrated as image 510). Typically, the angle Θ at which the detection line (indicated as image zone 504) is angled across the channel segment 502 will range from about 5-80 degrees from an axis Y perpendicular to the channel segment 502, more specifically 15-75 degrees, 20-70 degrees, 25-65 degrees, 30-60 degrees, 35-55 degrees, 40-50 degrees, or in some cases approximately 45 degrees. Though recited in terms of certain ranges, it will be understood that all ranges from the lowest of the lower limits to the highest of the upper limits are included, including all intermediate ranges or specific angles, within this full range or any specifically recited range. By angling the camera and the detection line/image zone 504, one achieves an effective closer spacing of the pixels as they image flowing materials. The resulting image thus is of higher resolution across the channel, as shown by image 512, than for the perpendicularly oriented image zone, as shown by image 510. By providing higher resolution, one is able to obtain higher quality images of the particles, droplets or other materials flowing through the channel segments of the device, and from that, derive the shape, size and other characteristics of these materials.

As will be appreciated, as the optical detection systems may be used to monitor flow rates within channel segments of a device, these detection systems may, as with the pressure monitoring systems described above, identify perturbations in the operation of the system. For example, where a reagent well is exhausted, allowing air to be passed through the channels of the device, while leading to a pressure drop across the relevant channel segments, it will also result in an increase in flow rate through that channel segment resulting from the lower fluidic resistance in that channel. Likewise, an obstructed channel segment will in many cases, lead to a reduced flow rate in downstream channel segments connected to the obstructed channel segment. As such, perturbations in flow rates measured optically, may be used to indicate system failures or run completions or the like. In general, perturbations of at least 5% in the optically determined flow rate, at least 10%, at least 20%, at least 30%, at least 40%, or at least 50%, will be indicative of a problem during a processing run, and may result in a system adjustment, shutdown or the like.

FIG. 8 illustrates optical monitoring processes and systems as described herein for use in identifying perturbations in flow within channels of a fluidic network. As shown, a single a microfluidic device, e.g., as shown in FIG. 2, is run under applied pressures at each of the various inlet reservoirs, e.g., reservoirs 230, 232 and 234, under constant pressure. The flow rate of droplets is measured within an outlet channel segment, e.g., channel segment 228 using an optical imaging system. The flow rate of a normally operating channel segment is plotted in the first portion 302 of the flow rate plot shown in FIG. 8. Upon exhaustion of one reagent, e.g., the oil in reservoir 234, air is introduced into the channel network, resulting in a reduced fluidic resistance, causing an increase in the flow rate, as shown in the second portion 304 of the plot.

VI. Reagent Detection

In addition to the components described above, in some cases, the overall systems described herein may include additional components integrated into the system, such components used to detect the presence and amount of reagents present in any reagent vessel component of the system, e.g., in a reservoir of a microfluidic device, an amplification tube, or the like. A variety of components may be used to detect the presence and/or amount of reagents in any vessel, including, for example, optical detection systems, that could include light transmission detectors that measure whether light is altered in passing through a reservoir based upon presence of a fluid, or machine vision systems that image the reservoirs and determine whether there is fluid in the reservoir and even the level of fluid therein. Such detection systems would be placed in optical communication with the reservoirs or other vessels of the system. In other cases, electrical systems may be used that insert electrodes into a reservoir and measure changes in current flow through those electrodes based upon the presence or absence of fluid within the reservoir or vessel.

VII. Additional Sensors/Monitoring

In addition to the sensing systems described above, a number of additional sensing systems may also be integrated into the overall systems described herein. For example, in some cases, the instrument systems may incorporate bar-code reader systems in one or more functional zones of the system. For example, in some cases, a barcode reader may be provided adjacent a stage for receiving one or more sample plates, in order to record the identity of the sample plat and correlate it to sample information for that plate. Likewise, barcode readers may be positioned adjacent a microfluidic device stage in a partitioning zone, in order to record the type of microfluidic device being placed on the stage, as reflected by a particular barcode placed on the device. By barcoding and reading the specific device, one could coordinate the specifics of an instrument run that may be tailored for different device types. A wide variety of barcode types and readers are generally used in research instrumentation, including both one dimensional and two dimensional barcode systems.

Other detection systems that are optionally integrated into the systems described herein include sensors for the presence or absence of consumable components, such as microfluidic devices, sample plates, sample tubes, reagent tubes or the like. Typically, these sensor systems may rely on one or more of optical detectors, e.g., to sense the presence or absence of a physical component, such as a plate, tube, secondary holder, microfluidic chip, gasket, etc., or mechanical sensors, e.g., that are actuated by the presence or absence of a plate, microfluidic device, secondary holder, tube, gasket, etc. These sensor systems may be integrated into one or more tube slots or wells, plate stages or microfluidic device stages. In the event a particular component is missing, the system may be programmed to provide an alert or notification as well as optionally or additionally preventing the start of a system run or unit operation.

II. Integrated Workflow Processes

The instrument systems described above may exist as standalone instruments, or they may be directly integrated with other systems or subsystems used in the particular workflow for the application for which the partitioning systems are being used. As used herein, integration of systems and subsystems denotes the direct connection or joining of the systems and/their respective processes into an integrated system or instrument architecture that does not require user intervention in moving a processed sample or material from a first subsystem to a second subsystem. Typically, such integration denotes two subsystems that are linked into a common architecture, and include functional interactions between those subsystems, or another subsystem common to both. By way of example, such interconnection includes exchange of fluid materials from one subsystem to another, exchange of components, e.g., plates, tubes, wells, microfluidic devices, etc., between two subsystems, and additionally, may include integrated control components between subsystems, e.g., where subsystems are controlled by a common processor, or share other common control elements, e.g., environment control, fluid transport systems, etc.

For ease of discussion, these integrated systems are described with respect to the example of nucleic acid applications. In this example, the partitioning instrument systems may be integrated directly with one or more sample preparation systems or subsystems that are to be used either or both of upstream and/or downstream in the specific overall workflow. Such systems may include, for example, upstream process systems or subsystems, such as those used for nucleic acid extraction, nucleic acid purification, and nucleic acid fragmentation, as well as downstream processing systems, such as those used for nucleic acid amplification, nucleic acid purification and nucleic acid sequencing or other analyses.

For purposes of illustration, the integration of the partitioning process components described above, with upstream and/or downstream process workflow components is illustrated with respect to a preferred exemplary nucleic acid sequencing workflow. In particular, the partitioning systems described herein are fluidly and/or mechanically integrated with other systems utilized in a nucleic acid sequencing workflow, e.g., amplification systems, nucleic acid purification systems, cell extraction systems, nucleic acid sequencing systems, and the like.

FIG. 6 schematically illustrates an exemplary process workflow for sequencing nucleic acids from sample materials and assembling the obtained sequences into whole genome sequences, contig sequences, or sequences of significantly large portions of such genomes, e.g., fragments of 10 kb or greater, 20 kb or greater, 50 kb or greater, or 100 kb or greater, exomes, or other specific targeted portions of the genome(s).

As shown, a sample material, e.g., comprising a tissue or cell sample, is first subjected to an extraction process 602 to extract the genomic or other nucleic acids from the cells in the sample. A variety of different extraction methods are commercially available and may vary depending upon the type of sample from which the nucleic acids are being extracted, the type of nucleic acids being extracted, and the like. The extracted nucleic acids are then subjected to a purification process 604, to remove extraneous and potentially interfering sample components from the extract, e.g., cellular debris, proteins, etc. The purified nucleic acids may then be subjected to a fragmentation step 606 in order to generate fragments that are more manageable in the context of the partitioning system, as well as optional size selection step, e.g., using a SPRI bead clean up and size selection process.

Following fragmentation, the sample nucleic acids may be introduced into the partitioning system, which is used to generate the sequenceable library of nucleic acid fragments. Within the partitioning system larger sample DNA fragments are co-partitioned at step 608, along with barcoded primer sequences, such that each partition includes a particular set of primers representing a single barcode sequence. Additional reagents may also be co-partitioned along with the sample material, including, e.g., release reagents for releasing the primer/barcode oligonucleotides from the beads, DNA polymerase enzyme, dNTPs, divalent metal ions, e.g., Mg2+, Mn2+, and other reagents used in carrying out primer extension reactions within the partitions. These released primers/barcodes are then used to generate a set of barcoded overlapping smaller fragments of the larger sample nucleic acid fragments at amplification step 610, where the smaller fragments include the barcode sequence, as well as one or more additional sequencing primer sequences.

Following generation of the sequencing library, additional process steps may be carried out prior to introducing the library onto a sequencer system. For example, as shown, the barcoded fragments may be taken out of their respective partitions, e.g., by breaking the emulsion, and be subjected to a further amplification process at step 612 where the sequenceable fragments are amplified using, e.g., a PCR based process. Either within this process step or as a separate process step, the amplified overlapping barcoded fragments may have additional sequences appended to them, such as reverse read sequencing primers, sample index sequences, e.g., that provide an identifier for the particular sample from which the sequencing library was created.

In addition, either after the amplification step (as shown) or prior to the amplification step, the overlapping fragment set may be size selected, e.g., at step 614, in order to provide fragments that are within a size nucleotide sequence length range that is sequenceable by the sequencing system being used. A final purification step 616 may be optionally performed to yield a sequenceable library devoid of extraneous reagents, e.g., enzymes, primers, salts and other reagents, that might interfere with or otherwise co-opt sequencing capacity of the sequencing system. The sequencing library of overlapping barcoded fragments is then run on a sequencing system at step 618 to obtain the sequence of the various overlapping fragments and their associated barcode sequences.

In accordance with the instant disclosure, it will be appreciated that the steps represented by the partitioning system, e.g., step 606, may be readily integrated into a unified system with any one or more of any of steps 602-606 and 610-618. This integration may include integration on the subsystem level, e.g., incorporation of adjacent processing systems within a unified system architecture. Additionally or alternatively, one or more of these integrated systems or components thereof, may be integrated at the component level, e.g., within one or more individual structural components of the partitioning subsystem, e.g., in an integrated microfluidic partitioning component.

As used herein, integration may include a variety of types of integration, including for example, fluidic integration, mechanical integration, control integration, electronic or computational integration, or any combination of these. In particularly preferred aspects, the partitioning instrument systems are fluidly and/or mechanically integrated with one or more additional upstream and/or downstream processing subsystems.

A. Fluidic Integration

In the case of fluidic integration, it will be understood that such integration will generally include fluid transfer components for transferring fluid components to or from the inlets and outlets, e.g., the reservoirs, of the fluidic component of the partitioning system. These fluid transfer components may include any of a variety of different fluid transfer systems, including, for example, automated pipetting systems that access and pipette fluids to or from reservoirs on the fluidic component to transfer such fluids to or from reservoirs, tubes, wells or other vessels in upstream or downstream subsystems. Such pipetting systems may typically be provided in the context of appropriate robotics within an overall system architecture, e.g., that move one or both of the fluidics component and/or the pipetting system relative to each other and relative to the originating or receiving reservoir, etc. Alternatively, such systems may include fluidic conduits that move fluids among the various subsystem components. Typically, hard wired fluidic conduits are reserved for common reagents, buffers, and the like, and not used for sample components, as they would be subject to sample cross contamination.

In one example, a fluid transfer system is provided for transferring one or more fluids into the reservoirs that are connected to the channel network of the fluidics component. For example, in some cases, fluids, such as partitioning oils, buffers, reagents, e.g., barcode beads or other reagents for a particular application, may be stored in discrete vessels, e.g., bottles, flasks, tubes or the like, within the overall system. These storage vessels would optionally be subject to environmental control aspects as well, to preserve their efficacy, e.g., refrigeration, low light or no light environments, etc.

Upon commencement of a system run, those reagent fluids would be transported to the reservoirs of a fluidic component, e.g., a microfluidic device, that was inserted into the overall system. Again, reagent transport systems for achieving this may include dispensing systems, e.g., with pipettors or dispensing tubes positioned or positionable over the reservoirs of the inserted device, and which are connected to the reagent storage vessels and include pumping systems.

Likewise, fluid transport systems may also be included to transfer the partitioned reagents from the outlet of the fluidic component, e.g., reservoir 238 in FIG. 2, and transported to separate locations within the overall system for subsequent processing, e.g., amplification, purification etc.

In other cases, the partitions may be maintained within the outlet reservoir of the fluidic component, which is then directly subjected to the amplification process, e.g., through a thermal controller placed into thermal contact with the outlet reservoir, that can perform thermal cycling of the reservoir's contents. This thermal controller may be a component of the mounting surface upon which the microfluidic device is positioned, or it may be a separate component that is brought into thermal communication with the microfluidic device or the reservoir.

However, in some cases, fully integrated systems may be employed, e.g., where the transfer conduits pass the reagents through thermally cycled zones to effect amplification. Likewise, alternative fluid transfer systems may rely upon the piercing of a bottom surface of a reservoir on a given device to allow draining of the partitions into a subsequent receptacle for amplification.

B. Mechanical Integration

In cases of mechanical integration, it will be understood that such integration will generally include automated or automatable systems for physically moving system components, such as sample plates, microfluidic devices, tubes, vials, containers, or the like, from one subsystem to another subsystem. Typically, these integrated systems will be contained within a single unified structure, such as a single casing or housing, in order to control the environments to which the various process steps, carried out by the different system components, are exposed. In some cases, different subsystem components of the overall system may be segregated from other components, in order to provide different environments for different unit operations performed within the integrated system. In such cases, pass-throughs may be provided with closures or other movable barriers to maintain environmental control as between subsystem components.

Mechanical integration systems may include robotic systems for moving sample containing components from one station to another station within the integrated system. For example, robotic systems may be employed within the integrated system to move lift and move plates from one station in a first subsystem, to another station in another subsystem.

Other mechanical integration systems may include conveyor systems, rotor table systems, inversion systems, or other translocation systems that move, e.g., a partitioning microfluidic device, tubes, or multiwall plate or plates, from one station to another station within the unified system architecture, e.g., moving a microfluidic device from its control station where partitions are generated to a subsequent processing station, such as an amplification station or fluid transfer station.

C. Examples of Integration

A number of more specific simple examples of integration of the aforementioned process components are described below.

In some cases, the up front process steps of sample extraction and purification may be integrated into the systems described herein, allowing users to input tissue, cell, or other unprocessed samples into the system in order to yield sequence data for those samples. Such systems would typically employ integrated systems for lysis of cell materials and purification of desired materials from non-desired materials, e.g., using integrated filter components, e.g., integrated into a sample vessel that could be integrated onto a microfluidic device inlet reservoir following extraction and purification. These systems again would be driven by one or more of pressure or vacuum, or in some cases, by gravitation al flow or through centrifugal driving, e.g., where sample vessels are positioned onto a rotor to drive fluid movements.

In some cases, it may be desirable to have sample nucleic acids size-selected, in order to better optimize an overall sample preparation process. In particular, it may be desirable to have one or more selected starting fragment size ranges for nucleic acid fragments that are to be partitioned, fragmented and barcoded, prior to subjecting these materials to sequencing. This is particularly useful in the context of partition-based barcoding and amplification where larger starting fragment sizes may be more desirable. Examples of available size selection systems include, e.g., the Blue Pippen® system, available from Sage Sciences (See also U.S. Pat. No. 8,361,299), that relies upon size separation through an electrophoretic gel system, to provide relatively tightly defined fragment sizes.

In accordance with the present disclosure, systems may include an integrated size selection system for generating nucleic acid fragments of selected sizes. While in some cases, these size selection components may be integrated through fluid transport systems that transport fragments into the inlet reservoirs of the fluidic components, e.g., pipetting systems, in certain cases, the size selection system may be integrated within the fluidic component itself, such that samples of varied fragment sizes may be input into the device by the user, followed by an integrated size separation process whereby selected fragment sizes may be allocated into inlet reservoirs for the fluidic components of the device.

For example, and as shown in FIG. 7, a size selection component 700 including a capillary or separation lane 702, is integrated into a microfluidic device. An electrophoretic controller is coupled to the separation lane via electrodes 704, 706 and 708 that apply a voltage differential across the separation matrix in lane 702 in order to drive the size-based separation of nucleic acid samples that are introduced into well 710. In operation, a separation voltage differential is applied across the separation lane by applying the voltage differential between sample reservoir 710 and waste reservoir 712. At the point in the separation at which the desired fragment size enters into junction 714, the voltage differential is applied between reservoir 710 and elution reservoir 716, by actuation of switch 718. This switch of the applied voltage differential then drives the desired fragment size into the elution reservoir 716, which also doubles as the sample inlet reservoir for the microfluidic device, e.g., reservoir 232 in FIG. 2. Once sufficient time has passed for direction of the desired fragment into reservoir 716, the voltage may again be switched as between reservoir 710 and waste reservoir 712.

Upon completion of the separation, fragments that have been driven into the sample elution reservoir/sample inlet reservoir, may then be introduced into their respective microfluidic partitioning channel network, e.g., channel network 720, for allocation into partitions for subsequent processing. As will be appreciated, in cases where an electrophoretic separation component is included within the system, e.g., whether integrated into the microfluidic device component or separate from it, the systems described herein will optionally include an electrophoretic controller system that delivers appropriate voltage differentials to the associated electrodes that are positioned in electrical contact with the content of the relevant reservoirs. Such systems will typically include current or voltage sources, along with controllers for delivering desired voltages to specified electrodes at desired times, as well as actuation of integrated switches. These controller systems, either alone, or as a component of the overall system controller, will typically include the appropriate programming to apply voltages and activate switches to drive electrophoresis of sample fragments in accordance with a desired profile.

As will be appreciated, a single microfluidic device may include multiple partitioning channel networks, and as such, may also include multiple size separation components integrated therein as well. These size separation components may drive a similar or identical size separation process in each of the different components, e.g., to provide the same or similar sized fragments to each different partitioning channel network. Alternatively, the different size separation components may drive a different size selection, e.g., to provide different sized fragments to the different partitioning networks. This may be achieved through the inclusion of gel matrices having different porosity, e.g., to affect different separation profiles, or it may be achieved by providing different voltage profiles or switching profiles to the electrophoretic drivers of the system.

As will be appreciated, for microfluidic devices that include multiple parallel arranged partitioning channel networks, multiple separation channels may be provided; each coupled at an elution zone or reservoir that operates as or is coupled to a different inlet reservoir for the partition generating fluidic network. In operation, a plurality of different separation channel components maybe provided integrated into a microfluidic device. The separation channels again are mated with or include associated electrodes for driving electrophoresis of nucleic acids or other macromolecular sample components, through a gel matrix within the separation channels. Each of the different separation channels may be configured to provide the same or differing levels of separation, e.g., resulting in larger or smaller eluted fragments into the elution zone/inlet reservoir of each of the different partitioning channel networks. In cases where the separation channels provide different separation, each of the different channel networks would be used to partition sample fragments of a selected different size, with the resulting partitioned fragments being recovered for each channel network in a different outlet or recovery reservoir, respectively.

3. Amplification

In some cases, the systems include integration of one or more of the amplification process components, e.g., steps 610 and 612, into the overall instrument system. In particular, as will be appreciated, this integration may be as simple as incorporating a temperature control system within thermal communication with the product reservoir on the fluidic component of the system, e.g., reservoir 238 in FIG. 2, such that the contents of the reservoir may be thermally cycled to allow priming, extension, melting and re-priming of the sample nucleic acids within the partitions by the primer/barcode oligonucleotides in order to create the overlapping primer sequences template off of the original sample fragment. Again, such temperature control systems may include heating elements thermally coupled to a portion of the fluidic component so as to thermally cycle the contents of the outlet reservoir.

Alternatively, the integration of the amplification system may provide for fluid transfer from the outlet reservoir of the fluidic component to an amplification reservoir that is positioned in thermal contact with the above described temperature control system, e.g., in a temperature controlled thermal cycler block, within the instrument, that is controlled to provide the desired thermal cycling profile to the contents taken from the outlet reservoir. As described above, this fluid transfer system may include, e.g., a pipetting system for drawing the partitioned components out of the outlet reservoir of the microfluidic device and depositing them into a separate reservoir, e.g., in a well of a multiwall plate, or the like. In another alternative configuration, fluid transfer between the microfluidic device and the amplification reservoir may be directed by gravity or pressure driven flow that is actuated by piercing a lower barrier to the outlet reservoir of the microfluidic device, allowing the generated partitions to drain or flow into a separate reservoir below the microfluidic device that is in thermal communication with a temperature control system that operates to thermally cycle the resultant partitions through desired amplification thermal profiles.

In a particular example, and with reference to the nucleic acid analysis workflow set forth above, the generated partitions from step 608 may be removed from the fluidics component by an integrated fluid transfer system, e.g., pipettors, that withdraw the created partitions form, e.g., reservoir 238 of FIG. 2, and transport those partitions to an integrated thermal cycling system in order to conduct an amplification reaction on the materials contained within those partitions. Typically, the reagents necessary for this initial amplification reaction (shown at step 610, in FIG. 6), will be co-partitioned in the partitions. In many cases, the integrated thermal cycling systems may comprise separate reagent tubes disposed within thermal cycling blocks within the instrument, in order to prevent sample to sample cross contamination. In such cases, the fluid transport systems will withdraw the partitioned materials from the outlet reservoir and dispense them into the tubes associated with the amplification system.

4. Size Selection of Amplification Products

Following amplification and barcoding step 610, the partitioned reagents are then pooled by breaking the emulsion, and subjected to additional processing. Again, this may be handled through integrated fluid transfer systems that may introduce reagents into the wells or tubes in which the sample materials are contained, or by transferring those components to other tubes in which such additional reagents are located. In some cases, mechanical components may also be included within the system to assist in breaking emulsions, e.g., through vortexing of sample vessels, plates, or the like. Such vortexing may again be provided within a set station within the integrated system. In some cases, this additional processing may include a size selection step in order to provide sequenceable fragments of a desired length.

5. Additional Processing and Sequencing

Following further amplification, it may be desirable to include additional clean up steps to remove any unwanted proteins or other materials that may interfere with a sequencing operation. In such cases, solid phase DNA separation techniques are particularly useful, including, the use of nucleic acid affinity beads, such as SPRI beads, e.g., Ampure® beads available from Beckman-Coulter, for purification of nucleic acids away from other components in fluid mixtures. Again, as with any of the various unit operations described herein, this step may be automated and integrated within the overall integrated instrument system.

In addition to integration of the various upstream processes of sequencing within an integrated system, in some cases, these integrated systems may also include an integrated sequencer system. In particular, in some cases, a single integrated system may include one, two, three or more of the unit process subsystems described above, integrated with a sequencing subsystem, whereby prepared sequencing libraries may be automatically transferred to the sequencing system for sequence analysis. In such cases, following a final pre-sequencing process, the prepared sequencing library may be transferred by an integrated fluid transfer system, to the sample inlet of a sequencing flow cell or other sequencing interface. The sequencing flow cell is then processed in the same manner as non-integrated sequencing samples, but without user intervention between library preparation and sequencing.

While the foregoing invention has been described in some detail for purposes of clarity and understanding, it will be clear to one skilled in the art from a reading of this disclosure that various changes in form and detail can be made without departing from the true scope of the invention. For example, all the techniques and apparatus described above can be used in various combinations. For example, particle delivery can be practiced with array well sizing methods as described. All publications, patents, patent applications, and/or other documents cited in this application are incorporated by reference in their entirety for all purposes to the same extent as if each individual publication, patent, patent application, and/or other document were individually and separately indicated to be incorporated by reference for all purposes. 

What is claimed is:
 1. An integrated system for processing samples comprised of various fluids for analysis, the system comprising: (a) a microfluidic device including a plurality of channel networks for partitioning the samples into partitioned samples, the plurality of channel networks being connected to a plurality of inlet and outlet reservoirs; (b) a holder including a closeable lid hingedly coupled thereto, wherein in a closed configuration, the closeable lid secures the microfluidic device in the holder, and wherein in an open configuration, the closeable lid comprises a stand orienting the microfluidic device at an angle to facilitate recovery of the partitioned samples; and (c) an instrument configured to receive the holder and apply a pressure differential between the plurality of inlet and outlet reservoirs to drive fluid movement within the plurality of channel networks.
 2. The integrated system of claim 1, wherein the angle at which the microfluidic device is oriented by the closeable lid ranges from about 20 degrees to about 70 degrees.
 3. The integrated system of claim 1, wherein the angle at which the microfluidic device is oriented by the closeable lid is approximately 45 degrees.
 4. The integrated system of claim 1, wherein the instrument comprises: (a) a retractable tray supporting and seating the holder, and slidable into and out of the instrument; (b) a depressible manifold assembly configured to be actuated and lowered to the microfluidic device and to sealaby interface with the plurality of inlet and outlet reservoirs; (c) at least one fluid drive component configured to apply the pressure differential between the plurality of inlet and outlet reservoirs; and (d) a controller configured to operate the at least one fluid drive component to apply the pressure differential depending on a mode of operation or according to preprogrammed instructions.
 5. The integrated system of claim 1, wherein at least a portion of one or more of the various fluids comprises reagents, wherein at least one of the plurality of channel networks comprises a plurality of interconnected fluid channels fluidly communicated at a first channel junction, at which an aqueous phase containing at least one of the reagents is combined with a stream of a non-aqueous fluid to partition the aqueous phase into discrete droplets within the non-aqueous fluid, and wherein the discrete droplets are stored in at least one outlet reservoir of the plurality of inlet and outlet reservoirs, or stored in at least one product storage vessel.
 6. The integrated system of claim 5, wherein the plurality of interconnected fluid channels comprises a microfluidic structure having intersecting fluid channels fabricated into a monolithic component part.
 7. The integrated system of claim 4, further comprising a gasket coupled to the holder and including a plurality of apertures, wherein, when the closeable lid is in the closed configuration, the gasket is positioned between the plurality of inlet and outlet reservoirs and the depressible manifold assembly to provide a sealable interface, and wherein the plurality of apertures allows pressure communication between at least one of the outlet and the inlet reservoirs and the at least one fluid drive component.
 8. The integrated system of claim 4, further comprising springs to bias the depressible manifold assembly in a raised position, and a servo motor to actuate and lower the depressible manifold assembly.
 9. The integrated system of claim 1, further comprising at least one monitoring component interfaced with at least one of the plurality of channel networks and configured to observe and monitor characteristics and properties of the at least one of the plurality of channel networks and fluids flowing therein, wherein the at least one monitoring component is selected from the group consisting of: a temperature sensor, a pressure sensor, and a humidity sensor.
 10. The integrated system of claim 1, wherein at least one channel of the plurality of channel networks comprises a channel segment that widens and controls flow by breaking capillary forces acting to draw aqueous fluids into the at least one channel.
 11. The integrated system of claim 10, further comprising a passive check valve comprising the channel segment.
 12. The integrated system of claim 1, wherein at least one of the plurality of channel networks comprises: a first channel segment fluidly coupled to a source of barcode reagents; a second channel segment fluidly coupled to a source of a sample of the samples, the first and second channel segments fluidly connected at a first channel junction; a third channel segment connected to the first and second channel segments at the first channel junction; a fourth channel segment connected to the third channel segment at a second channel junction and connected to a source of partitioning fluid; and a fifth channel segment fluidly coupled to the second channel junction and connected to a channel outlet, wherein the instrument is coupled to at least one of the first, second, third, fourth, and fifth channel segments, and is configured to drive flow of the barcode reagents and the sample into the first channel junction to form a reagent mixture in the third channel segment and to drive flow of the reagent mixture and the partitioning fluid into the second channel junction to form droplets of the reagent mixture in a stream of partitioning fluid within the fifth channel segment.
 13. A holder assembly, comprising: (a) a holder body configured to receive a microfluidic device, the microfluidic device including a plurality of parallel channel networks for partitioning various fluids; and (b) a closeable lid hingedly coupled to the holder body, wherein in a closed configuration, the closeable lid secures the microfluidic device in the holder body, and in an open configuration, the closeable lid comprises a stand to orient the microfluidic device at an angle to facilitate recovery of partitioned fluids without spilling the partitioned fluids.
 14. The holder assembly of claim 13, wherein the angle at which the microfluidic device is oriented by the closeable lid ranges from about 20 degrees to about 70 degrees.
 15. The holder assembly of claim 13, wherein the angle at which the microfluidic device is oriented by the closeable lid is approximately 45 degrees.
 16. The integrated system of claim 1, wherein each of the plurality of channel networks are parallel with one another.
 17. The integrated system of claim 1, wherein the angle at which the microfluidic device is oriented by the closeable lid ranges from about 30 degrees to about 60 degrees.
 18. The integrated system of claim 1, wherein the angle at which the microfluidic device is oriented by the closeable lid ranges from about 40 degrees to about 50 degrees. 